Chelating compositions and detergent compositions pertaining to same

ABSTRACT

Chelating compositions comprising 97 - 70 percent PVM/MA copolymer and 3 - 30 percent borax, detergent, dyeing, scouring and like compositions containing the same and process for chelating calcium, magnesium, iron, manganese and the like ions using the chelating compositions of the invention.

United States Patent [191 Cooney Dec. 3, 1974 1 CHELATING COMPOSITIONS AND DETERGENT COMPOSITIONS PERTAINING TO SAME [75] Inventor: William J. Cooney, l-lixson, Tenn. [73] Assignee: GAF Corporation, New York, NY.

[22] Filed: Jan. 12, 1972- [21 App]. No.: 217,225

[52] US. Cl 252/181, 210/58, 252/DIG. 11, 252/135, 252/180 [51] Int. Cl C02b 5/00 [58] Field of Search 252/181, 180, DIG. 11, 252/135; 210/58 [56] References Cited UNITED STATES PATENTS 3,623,991 11/1971 Sabatelli et a1, 252/180 7/1972 Dittel et a1. 252/135 10/1972 Mizano et al. 252/135 X OTHER PUBLICATIONS Gantrez An Geneve Aniline & Film Corp., N. Y., N.Y., page 16 relied on, pub. 1961.

Primary Examiner-Mayer Weinblatt Attorney, Agent, or Firm-Walter C. Kehm; Samson B. Leavitt- 5 7 ABSTRACT 1 Claim, No Drawings COMPOSITIONS PERTAINING TO SAME Ethylenediaminetetra acetic acid EDTA Nitrilotriacetic acid NTA Hexamethylenediaminetetra acetic acid HEDTA Sodium tripolyphosphate STPP Diethylene Triamine Pentaacetic acid DTPA.

citric acid, gluconic acid and glucoheptonate. Thereare numerous problems associated with the use of the polyphosphates and NTA,.particularly in the area of pollution of streams, rivers and other drinking water sources while serious health problems, including death, have been reported in connection with the use of EDTA, NTA, HEDTA and DTPA. The use of citric acid, gluconic acid and glucoheptonate has also not proven successful because of the low chelating power of these agents and the requirement that they be used in large concentrations. g

It has already been proposed to use PVM/MA copolymers as chelating agents in detergent and cleaning formulations. It is well known that such copolymers are non-toxic to both animals, fish and humans. Unfortunately, however, hydrolyzed PVM/MA copolymers have not been capable of chelating metal ions to the degree required for commercial acceptance.

In accordance with the invention, it has now been found that compositions comprising PVM/MA and borax are capable of chelating metal ions such as calcium, magnesium, iron, and manganese to a degree not possible with the PVM/MA copolymers alone, such compositions constituting commercially acceptable chelates.

A feature of the invention is the provision of compositions comprising 3 30 percent borax and 97 70 percent PVM/MA.

As used herein, the term borax designates hydrated sodium tetrabo'rate'ln the preferred practice of the invention, borax sodium tetraborate is used either in its refined or crude state. Typical analyses of these two particular borates are as follows:

Crude Borax Ore Chemical Analysis Weight Percent Boric oxide (B 0 Sodium oxide (Na O) Iron oxide (Fe,O Aluminum oxide (M 0 Titanium oxide (TiO Silica (SiO Calcium oxide (CaO) Magnesium oxide (MgO) Carbon dioxide (CO- Water (H O) Water insoluble Fine Granulated Borax Chemical Analysis Weight Percent Boron trioxide (B 0 36.3 38.3 Sodium oxide' (Na O) 16.2 17.1 Water (H O) 44.6 47.5 Anhydrous borax (Na B,,O 52.5 55.4 Equivalent borax (Na B,,O .l0H O) 99.5 105.0

In addition to the borax, crude or refined other boron compounds can be used provided that they can serve for the necessary pH control and furnish the water necessary for hydrolysis of the'anhydride. Such boron compounds include inorganic alkali metal boron compounds, i.e., alkali metal borates, NaBO .2I-I O, Na B- O .5H O, NaBO Ll-I O, NaBO .4H O, K B O .5H O, LiBO .8I-I O and their corresponding acids as well as organic borate esters such as boron acetate, tricyclohexyl borate, tri-n-dodecyl borate, tri-(Z- ethylhexyl) borate, etc.

The PVM/ MA copolymers employed in the compositions of the invention are known materials and are characterized by the following unit structural formula:

mers suitable for use in this invention have a specific viscosity of from about 0.1. to about 3.5 and, preferably, have a specific viscosity of from about 0.1 to about 0.5. The specific viscosity, as used herein, is determined from a solution of l gram of the copolymer in ml. of methylethyl ketone at 25C. As is well known in the art, molecular weight is directlyrelated tothe specific viscosity.

The ability of the compositions comprising the PVM/ MA copolymer and borax or other suitable boron compound-to complex calcium, magnesium and other polyvalent metal ions is determined by analytical procedures in which the complexing agent is titrated with calcium in the presence of an indicator.

The first chelating agent to be introduced to the chemical industry in the United States was EDTA. This compound was widely adopted because of its then unique ability to complex calcium and magnesium, as well as other polyvalent metal ions. Until the introduction of NTA by Hampshire Chemical Corporation, only ethylenediamine or substituted ethylenediamine-based chelating agents were suitable for use as amino acid sequestering agents for calcium and magnesium.

The analytical procedure currently used throughout the chemical industry to test ethylenediamine-based chelating agents is one in which the complexing agent is titrated with calcium in the'presence of an indicator, which, in reality, is a precipitant for the metal ion. The chelating agent reacts with the metal ion as it is added to the system until the chelate is exhausted or reaches an equilibrium wherein the metal ion present is in excess of the amount required to react with the indicator it was found that the oxalate test was valid for ethylenediarnine only or substituted ethylenediamine-based compounds and that other chelating agents, most of which would not complex calcium, required other analytical procedures. In other words, the oxalate method I is a special case analytical method.

The oxalate indicator, because of the great insolubility of calcium oxalate, gives a premature end point with NTAwhich masks its useful chelating power. if a true indication of NTAs chelating ability is to be measured accurately, either Schwartzenbachs method which is accurate with any chelating agent or the calcium titration with a Na CO5 indicator is required to be used.

Although the oxalate titration method is a good method-of control, the oxalate method is not suitable for all types of sequestering or chelating agents. Oxalate is useful, however, for comparing the relative sequestering power of ethylenediamine-based chelating agents. I

The three basic methods presently used to evaluate the sequestering power of chelating agents include the following:

Carbonate Method Reagentsi Calcium acetatesolution'QS 44.1 gm. (monomgm. CaCOgcc.) hydrate )lliter Sodium carbonate 2% solution Sodium hydroxide lN.

Procedure? v Weigh accurately a 2 gram sample of dry sequestering material ora 5 gram sample of a liquid solution thereof and dissolve in approximately 50 ml. of distilled water. If the material is not sufficiently soluble, for instance NTA acid, sufficient sodium hydroxide must be used to provide solubility. Add 10 ml. of sodium carbonate solution. Adjust the pH to l l-l2 and bring the total volume up to lOO ml. Titrate with calcium acetate to a distinct and permanent turbidity. The end point is conclusively determined-after taking the burette reading by the addition of a few more drops which then cause a distinct clouding of the 'titrating medium.

Calculations:

Q11 calcium acetate) X25 weight sample =milligrnrns of CaCO chelatedper gram I A slightly more precise but somewhat more time- 'consuming method is the Schwartzenbach method.

Schwartzenbach Method Reagents:

, Copper chloride solution 0.1M. Sodium hydroxide solution 0.1000 N.

Hydrochloric acid Concentrated and 0.l N.

Procedure:

Weigh accurately 1 gram of the sample to be assayed. Dissolve the sample in 50 ml. of water or in l N. caustic to dissolve the less soluble sequestering agent. Measure the pH of the copper chloride solution and adjust the sample to the same pH. Add the copper chloride solution in l ml. quantities. The ph will drop as the copper is chelated. Titrate the solution with 0.1000 N. NaOH back to the pH of the 0.1 M. copper chloride. Continue the addition of copper chloride solution and the back titration with caustic until there is no lowering of pH on the addition of the copper solution. A second titration made by adding at once 1 cc. less of the acid used in the first titration and then making the final addition in l ml. increments will give an accurate end point. Calculation: v

(ml. of NaOH) xinonmtiii of NaOH) Weight of sample Milligrams of (31100 ehelated per gram Oxalate Method The above finding has application to the formulation of detergent compositions particularly those used in socalled hard water areas. The compositions of the invention also lend themselves to use in pollution protection,

to processes for water treatment and purification, to drilling operations and the like.

In connection with water treatment, the compositions of the invention can be used for thechemical treatment of water to prevent the formation of insoluble calcium and magnesium soaps and other hard water ions from precipitating in systems using large quantities of water. The softening of water both for industrial and non-industrial use is improved not only with respect to washing operations but also in avoiding the deposition of scale in boilers, condensers, heat exchangers or-conditioning systems and the like.

The compositionsof the invention can also be used for the treatment of water for the purpose of clarifying the same. Addition of the compositions of the invention to turbid river. water, for instance, results in the removal by sequestering of the substances giving rise to the turbidity.

Most important, the PVM/ MA bo'rax compositions of the invention can be incorporated into detergents resulting in improved detergency, i.e., enhanced cleaning capacity. In general, the compositions of the invention can be incorporated into liquid and solid detergents where the essential ingredients are, in addition to the compositions of the invention, at least one organicwater-soluble detergent surface active material. The detergent surface active compounds which can be used within the compositions of the invention include anionic, non-ionic, zwitterionic, ampholytic detergent compounds and mixtures thereof.

Instances of anionic detergent compounds include both soap and non-soap detergent compounds. Examples of suitable soaps are sodium, potassium, ammonium and alkylol ammonium salts of higher fatty acids (C Examples of anionic organic non-soap detergent compounds are the water-soluble salts, alkali metal salts. of organic sulfuric reaction products having in their molecular structure an alkyl group containing from about 8 to 22 carbon atoms and a sulfonic acid or sulfuric acid radical.

Non-ionic synthetic detergents may be broadly defined as aliphatic or alkylaromatic in nature which do not ionize in water solution. This includes the wellknown class of non-ionic synthetic detergents marketed under the trade name of Pluronic." These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by condensation of propylene oxide with propylene glycol.

Ampholytic synthetic detergents can be broadly de-- scribed as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical may be straight chain or branched and wherein one of the aliphatic substituents contains about 8 to 18 carbon atoms and one contains an anionic water-solubilizing group. This class of compounds include sodium-3- dodecylaminopropionate and sodium-3- dodecylaminopropanesulfonate.

Zwitterionic synthetic detergents can be broadly described as derivatives of aliphatic quaternary amino compounds in which the aliphatic radical may be straight or branched chain and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water-solubilizing group. Examplesof compounds in this group are 3- (N,N-dimethyl-N-hexade cylammonio)propanel sulfonate and 3-(N,N-dimethyl-N- hexadecylammonio)-2-hydroxy-propane-1-sulfonate.

The foregoing organic surfactants can be used singly or in combination. a

The detergent compositions can be formulated in any of the commercially desirable composition forms, for example, granulated, foam, liquid or tablet.

Further, the compositions of, the invention can contain the conventional ingredients in minor amounts, such as soil redeposition inhibitors, such as soluble sodium carboxymethylcellulose, corrosion and tarnish inhibitors, such as soluble silicates, benzotriazole or ethylenethio-urea, sodium sulfate and sodium carbonate.

The following examples serve to illustrate but not limit the present invention.

EXAMPLE 1 4.5 grams of PVM/MA copolymer were dissolved 'in 85 grams of water at l50-l60F. 2.5 grams of borax were then added and the resultant solution allowed to cool.

The ability of the resultant material to chelate calcium was determined by'using the calcium carbonate titration procedure above set out and amounted to 100 mg. CaCo per gram of composition.

EXAMPLE 2 12.5 grams of PVM/MA were dissolved in 87 grams of water at 150% l60F 0.5 grams of borax were then added and the resultant material allowed tocool. The ability of the composition to chelate calcium was determined by the carbonate method above described and amounted to 100 mg. of calcium carbonate per gram of composition.

EXAMPLE 3 EXAMPLE 4 grams of PVM/MA in powder form were dryblended with 20 grams of borax. 1 gram of the resultant mix was dissolved in hot water having a temperature of l501 60F. When tested for chelating ability, according to the calcium carbonate method,'this mixture was capable of chelating 627 mg. calcium carbonate per gram of composition.

The solution produced, in accordance with Example 4, compared with EDTA and the polyphosphates in ability to chelate iron, copper and calcium.

The composition of the invention was incorporated in conventional dyeing, bleaching and scouring agents for use in the treatment of cotton and cotton-polyester materials. The materials of the invention were, in each instance, found to be at least the equivalent of the EDTA and'the polyphosphates for the purpose investigated. e

EXAMPLE 5 Y A detergent-composition having the following compositions was prepared:

' Percent PVM/MA-borax (80:20) 2 Sodium dodecylbenzosulfonate 6 Dimethyldodecylamino oxide 6 Potassium toluene sulfonate 8 Sodium silicate (SiO :Na O=2.45:l) 3.8 Carhoxy methyl hydroxy ethyl cellulose 0.3

- Triton X-l00 (condensation product of isooctyl phenol 10 moles of ethylene oxide) 20 Water balance This composition performed extremely well in hard water laundry usage as well as in hard water dish washing usage.

EXAMPLE 6 A superior cleaning and whitening liquid detergent composition was prepared having the following ingredients:

Water balance The following detergent composition was prepared:

Condensation product of dodecylphenol and ethylene oxide ll moles of ethylene oxide per mole of dodecylphenol) Polyethylene glycol ether of isooctylphenol (containing about 8 to 10 ethyleneoxy groups) Sodium silicate (SiO :Na O=2.5:l)

Potassium toluene sult'onate Sodium sulfate PVM/MA borax (75:25)

Water balance What is claimed is:

Percent l. The method of preparing a chelating composition consisting essentially of 97-7O percent of a polyvinyl methyl ether-maleic anhydride copol'ymer characterized by the formula:

mixture in water. 

1. THE METHOD OF PREPARING A CHELATING COMPOSITION CONSISTING ESSENTIALLY OF 97-70 PERCENT OF A POLYVINYL METHYL ETHERMALEIC ANHYDRIDE COPOLYMER CHARACTERIZED BY THE FORMULA: 